Implementation and analysis of IP multicast over ATM

Today it is evident that ATM technology will have its role in the future of internetworking. Two major Internet backbone service providers, Sprint and MCI, have marketed their investments in ATM as a way to push more bandwidth into their Internet infrastructures. Regardless of whether ATM technology will thrive in the WAN or LAN, it is also evident that the Internet Protocol (IP), which has been the glue of the Internet allowing it to endure exponential growth, must be well supported over ATM. IP multicast (protocol extensions to IP that allow IP packets from one source to be distributed to multiple destinations) is an essential part of IP which has allowed multimedia applications, for example, to more efficiently use Internet resources. In this paper we describe an implementation of one model of supporting IP multicast over ATM, the Multicast over ATM model developed by the IETF (Armitage, 1996). We discuss empirical measurements gathered in a testbed with both a WAN and a LAN component that give insights into the behavior of this model. We detail some of the shortcomings of this model and discuss potential modifications to improve it. Ideas for other approaches to IP multicast over ATM are also described